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Quantification of cow milk yield and pre-weaning calf growth response in temperate pasture-based beef suckler systems: A meta-analysis
Sapkota, D. Kelly, A.K. Crosson, P. White, R.R. McGee, M.
Sapkota, D.
Kelly, A.K.
Crosson, P.
White, R.R.
McGee, M.
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2020-08-19
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D. Sapkota , A.K. Kelly , P. Crosson , R.R. White , M. McGee , Quantification of cow milk yield and pre-weaning calf growth response in temperate pasture-based beef suckler systems: A meta-analysis, Livestock Science (2020), doi: https://doi.org/10.1016/j.livsci.2020.104222
Abstract
The objectives of this study were to quantitatively summarize factors
associated with cow milk yield (MY) and calf growth response in pasture-based beef
cow-calf suckler systems and to discern how cow genotype and parity influenced
these responses. A dataset of 344 treatment mean observations was compiled from
69 studies that reported data on cow MY, and calf pre-weaning average daily live
weight gain (ADG) and/or weaning weight (WW). Data were analysed using linear
mixed effects models with study and region included as random effects. Models were
developed for cow MY, calf ADG and WW response and each model was evaluated
based on different model fit statistics. The final cow MY model included cow origin
(Dairybeef or Beef), cow maturity (early-maturing (EM) or late-maturing (LM)
genotypes) and parity. Dairybeef produced 35.4% more milk (8.64 vs. 6.38 kg/day)
than Beef cows, and LM produced 20.9% more milk (8.20 vs. 6.78 kg/day) than EM
genotypes (P < 0.001). Multiparous cows had a 14.8% higher MY (8.11 vs. 7.06
kg/day) compared to primiparous cows (P < 0.001). Lactation curve persistency was
better (P < 0.05) for Beef and EM compared to Dairybeef and LM genotype cows,
respectively. The final models of calf ADG and WW included cow origin, cow
maturity and parity. Calves from Dairybeef and LM cows were 14 and 20 kg heavier
(P < 0.001) at weaning (210-day adjusted) compared to those from Beef and EM
genotype cows, respectively. Calves from multiparous cows were 13 kg heavier at
weaning than those from primiparous cows (P < 0.001). The response in calf ADG
associated with a 1 kg increase in cow daily MY was 47 and 53 g for Dairybeef and
Beef cows, respectively (P<0.001). Corresponding responses for EM and LM cows
were 51 and 55 g (P<0.001). In conclusion, the relationships between cow MY and
calf pre-weaning growth, as well as the quantitative impact of cow genotype and
parity were determined for pasture-based beef suckler systems; the coefficients
generated can be used for improving beef cow-calf management strategies, beef
cattle breeding programmes and bio-economic modelling purposes.